The invention relates to the construction of a ram that is utilized in high speed apparatus for forming elongated one piece metal can bodies from relatively shallow cups, and more specifically relates to an improved lightweight ram with increased integrity against stresses produced during the operation of the bodymaker.
The main section or body of a so-called two piece metal container or can of the type very often used for beer/beverages includes an elongated cylindrical sidewall, an integral bottom and an open top. Such bodies are often formed in drawing and ironing machines of the type described in U.S. Pat. No. 3,704,619 issued Dec. 5, 1972 to E. Paramonoff for Redraw Blankholder Positioning Mechanism for Cup-shaped Article Formers such as Metallic Can Body Formers and the Like, U.S. Pat. No. 3,735,629 issued May 29, 1973 to E. Paramonoff entitled Apparatus for Forming One Piece Metallic Can Bodies, and U.S. Pat. No. 4,530,228 issued Jul. 23, 1985 to W. Snyder and D. Dettmer for Apparatus for Producing Seamless Container Bodies. The apparatus described in the aforesaid patents produce can bodies from blanks in the form of relatively shallow cups, by having a reciprocated ram drive each cup through a die pack which is a series of ringlike die elements having openings that are graduated. Each blank passes through the largest opening first, and each subsequent opening that the blank is driven through is slightly smaller than the preceding opening through which the blank has been driven.
A replaceable punch mounted to the ram at the front thereof engages each cup to drive it through the die pack. The rear end of the ram is connected to the drive means that reciprocates the ram along its horizontally positioned longitudinal axis through a forward working stroke followed by a rearward return stroke.
Conventionally, rams are manufactured from a single piece of barstock. This imposes severe limitations on readily machining the interior of the hollow elongated main center section of the ram. This problem arises because the axial passages at both ends of the ram are limited in diameter, being considerably less than the center section diameter that will still enable the center section to provide the required mechanical strength (without having excessive wall thickness). Thus, in the prior art, wall thickness of the main center section was unusually considerably greater than necessary to meet strength requirements, so that the rams were unnecessarily heavy.
In U.S. Pat. No. 5,208,435 a ram is provided constructed as a weldment in which there is an elongated tube, a tail piece metallurgically bonded to one end of the tube and a nose piece metallurgically bonded to the other end of the tube. While effective, this ram could experience excessive stress levels in the weld zones with the effects of these stresses being magnified when the welds have imperfections.